Diesel Hybrids
Created July 2, 2006, at 10:48 pm by Anonymous
I was reading a Wired magazine recently and it mentioned something about how diesel hybrids will be released (based on the new cleaner burning diesel standards in the US) in the US in the few years. It is likely that they will get far superior gas mileage to compared to their spark ignited brethren. The problem is that I have not heard anything of the sort. Sure, the logical step has always been there, but I haven't heard anything about any real upcoming vehicles.
Anybody got any news to share??
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The diesel hybrid sounds like a marvel idea, but due to the diesel's characteristics, I've heard that it really isn't that great.
The primary reason is that diesel does not like to shut down and restart like a gasoline engine. That is why if you pull into a rest stop along a highway at night, when all of the truck drivers are down, you will notice many of them leave their engines idleing the entire night, its just more efficient than shutting them down and restarting in the morning.
Diesels are direct injection. A few direct injection
gasoline are finally coming to the US. The direct
injection engines can run on a fuel-air mix as low
as 1:64 while the common gasoline fuel injected
engine need 1:14.7 Thats why there is nor so much to gain to make a diesel-hybrid. The diesel is
already extremely frugal in slow traffic and at idle.
Once the low sulphur gasoline comes here in September the DI gasoline will get the same benefits
Tim,
It's not true that diesels don't like to stop and restart. VW pioneered the "3-Liter" Lupo a few years back, with a small displacement direct-injection diesel, that got better than 3 L/100 km fuel consumption (79 mpg). It used "auto-stop" when the car was stopped, and the engine started right up again when stepping on the accelerator.
Modern DI diesels with high-performance glow plugs start easily from cold after only a few seconds of preheat; our VW TDIs start no sweat in temperatures down to -40. When warm, the engines light off instantly.
You can't compare big rigs to diesel cars; indeed the big rigs are hard to start from cold.
Mike G, you're most likely true on being able to "auto-stop" a small diesel.
But as bjorn stated, there is not much sense in a diesel-hybrid, because of the efficiency of direct injection.
The hybrid offset most of the disadvantage the indirect
fuel injection system has over direct injection (being
gas or diesel) by shutting down the engine under light
load. Thats when the indirect gas engine runs with
the uneeded gas/air mix for power, but it is necessary
to make the the engine run smooth and the catalyc
converter hot to clean the sulphur coming from the
engine. With direct injection engine and ultra low sulphur
gasoline that problem is gone and the fues saving can be 20%.
If you'd like to see a new diesel-electric concept car they will be at this years http://www.hybridfest.com
Working EV-1 and plug-in hybrids too.
Sounds like a great weekend ahead in Madison!
Who ever thinks its just as efficent to idle a diesel doesn't own a trucking fleet, a misconception people have is thinking fleet owners want drivers to idle to save components, wrong, we only allow idling to provide heat or ac for the driver and are currently testing 6 trucks with Batt. Hvac systems and 6 trucks with APU's, we have 80 Class 8 Tractors, are they lose approx. 1 mpg. when they idle 50%, and at 120k mile per yr. at a average of 5.5 mpg that is 21818 gallons of fuel, now with idling 18461 gallons= 3357 gallons a yr. saved at $3 per gallon=$10,071 per truck X 80 trucks= $805680.00 per year more. now my new trucks have a 3yr warranty that would cover a starter, 3 years no idle would save my fleet $2,417,040.00 in fuel, we could afford to buy a few starters after that, and yes these engines start with a tap to the starter which would work very good for start/stop driving
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